Hello.. I'm tring to figure out if i have a thermocouple or flame sensor in my furnace. Its prob 15-20 yrs old. upon [email protected] the furnace it looks to be a standing pilot assembly, it has a pilot burner and what looks to be a thermocouple but it has ceramic on it like a flame sensor and is connected by a thick orange wire with a screw on attachment at both ends not a copper tube. The tip from ceramic to tip end is also very short 1/2 inch or so....Been doing research because my furnace fires up then 5 seconds later it clicks off then few seconds later fires up again and does this over and over until the cycle ends. It does not do it all the time sometimes its one or two clicks and others its for the entire cycle duration... I did clean the tip off with steel wool and was hoping this is the problem but dont know what replacement to look for cause everything i have seen for a thermocouple is a copper tube attached to it and the flame sensors have a flat metal prong with a hole at the end... please help me...

 

a thermocouple would go to the gas valve. a flame sensor would go to the circuit board.